Subacute Bacterial Endocarditis (SBE): Presentation, Diagnosis & Treatment

Subacute bacterial endocarditis (SBE) is an indolent infection of the endocardium, typically caused by low-virulence streptococci (e.g., Streptococcus viridans) or enterococci. It evolves over weeks to months, often on structurally abnormal valves.

Clinical Features

• Fever (low-grade, intermittent), chills, night sweats
• Fatigue, weight loss, anorexia
• New or changing heart murmur (most consistent sign)
• Embolic phenomena: splinter hemorrhages, Janeway lesions, Osler nodes, Roth spots, stroke
• Immune complex manifestations: glomerulonephritis, vasculitis

Diagnosis

• Blood cultures: 3 sets over 24 hours (95% sensitivity).
• Echocardiography: TEE preferred; detects vegetations, abscess, regurgitation.
• Modified Duke Criteria: Combines microbiological, echocardiographic, and clinical findings.

Treatment

• IV antibiotics: 4–6 weeks tailored to organism (e.g., penicillin + gentamicin for susceptible viridans strep).
• Surgery indicated for: Heart failure, uncontrolled infection, abscess, recurrent emboli, large vegetations (>10 mm), fungal/prosthetic valve infection.

Prophylaxis

Antibiotic prophylaxis before dental procedures for high-risk patients (prosthetic valve, prior endocarditis, certain congenital heart diseases, cardiac transplant with valve disease).